U.S. patent application number 14/405549 was filed with the patent office on 2015-05-14 for system and method of monitoring and control of ultrafiltration volume during peritoneal dialysis using segmental bioimpedance.
This patent application is currently assigned to Fresenius Medical Care Holdings, Inc.. The applicant listed for this patent is Fresenius Medical Care Holdings, Inc.. Invention is credited to Nathan W. Levin, Fansan Zhu.
Application Number | 20150133854 14/405549 |
Document ID | / |
Family ID | 49712702 |
Filed Date | 2015-05-14 |
United States Patent
Application |
20150133854 |
Kind Code |
A1 |
Zhu; Fansan ; et
al. |
May 14, 2015 |
SYSTEM AND METHOD OF MONITORING AND CONTROL OF ULTRAFILTRATION
VOLUME DURING PERITONEAL DIALYSIS USING SEGMENTAL BIOIMPEDANCE
Abstract
A peritoneal dialysis (PD) system for infusing a volume of PD
solution into a patient's peritoneal cavity in order to perform
peritoneal dialysis on the patient includes a peritoneal cavity
monitor (PCM) that measures this volume of fluid in the patient's
peritoneal cavity by segmental bioimpedance spectroscopy (SBIS), to
thereby determine an ultrafiltration volume of fluid in the
patient's peritoneal cavity, and a switch, controlled by the PCM,
for filling the patient's peritoneal cavity and draining the
patient's peritoneal cavity when the ultrafiltration volume is
unchanged over time, significantly decreased, or decreasing at a
significant rate.
Inventors: |
Zhu; Fansan; (Flushing,
NY) ; Levin; Nathan W.; (New York, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fresenius Medical Care Holdings, Inc. |
Waltham |
MA |
US |
|
|
Assignee: |
Fresenius Medical Care Holdings,
Inc.
Waltham
MA
|
Family ID: |
49712702 |
Appl. No.: |
14/405549 |
Filed: |
June 7, 2013 |
PCT Filed: |
June 7, 2013 |
PCT NO: |
PCT/US13/44795 |
371 Date: |
December 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61657271 |
Jun 8, 2012 |
|
|
|
Current U.S.
Class: |
604/28 ;
604/29 |
Current CPC
Class: |
A61M 2205/3379 20130101;
A61M 2205/3569 20130101; A61M 2205/3344 20130101; A61M 2210/1017
20130101; A61M 2230/005 20130101; A61B 5/6866 20130101; A61M
2205/3317 20130101; A61M 2205/3592 20130101; A61M 1/282 20140204;
A61B 5/1451 20130101; A61M 2205/17 20130101; A61M 1/281 20140204;
A61M 1/28 20130101; A61B 5/4848 20130101; A61M 1/284 20140204; A61M
2205/18 20130101 |
Class at
Publication: |
604/28 ;
604/29 |
International
Class: |
A61M 1/28 20060101
A61M001/28; A61B 5/00 20060101 A61B005/00; A61B 5/145 20060101
A61B005/145 |
Claims
1. A peritoneal dialysis (PD) system for infusing a volume of PD
solution into a patient's peritoneal cavity in order to perform
peritoneal dialysis on the patient, the system comprising: a
peritoneal cavity monitor (PCM) that measures the volume of fluid
in the patient's peritoneal cavity by segmental bioimpedance
spectroscopy (SBIS), to thereby determine an ultrafiltration volume
of fluid in the patient's peritoneal cavity; and a switch,
controlled by the PCM, for filling the patient's peritoneal cavity
and draining the patient's peritoneal cavity when the
ultrafiltration volume is unchanged over time, significantly
decreased, or decreasing at a significant rate.
2. A peritoneal dialysis (PD) system for infusing a volume of PD
solution into a patient's peritoneal cavity in order to perform
peritoneal dialysis on the patient, the system comprising: a
peritoneal cavity monitor (PCM) that measures the volume of fluid
in the patient's peritoneal cavity by segmental bioimpedance
spectroscopy (SBIS), to thereby determine an ultrafiltration volume
of fluid in the patient's peritoneal cavity; and an alarm,
controlled by the PCM, for indicating when the patient's peritoneal
cavity is to be drained when the ultrafiltration volume is
unchanged over time, significantly decreased, or decreasing at a
significant rate.
3. The peritoneal dialysis (PD) system of claim 2, wherein the
switch is controlled by the PCM by wireless communication.
4. A method of peritoneal dialysis of a patient, the method
comprising: a) introducing a volume of peritoneal dialysis solution
into the peritoneal cavity of the patient; b) measuring
periodically the volume of fluid in the patient's peritoneal cavity
by segmental bioimpedance spectroscopy (SBIS), to thereby determine
an ultrafiltration volume of fluid in the patient's peritoneal
cavity; and c) draining the patient's peritoneal cavity when the
ultrafiltration volume is unchanged over time, significantly
decreased, or decreasing at a significant rate.
5. The method of claim 4, further including refilling the
peritoneal cavity of the patient with another volume of peritoneal
dialysis solution.
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/657,271, filed on Jun. 8, 2012. The entire
teachings of the above application are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] Renal dysfunction or failure and, in particular, end-stage
renal disease, causes the body to lose the ability to remove water
and minerals and excrete harmful metabolites, maintain acid-base
balance, and control electrolyte and mineral concentrations within
physiological ranges. Toxic uremic waste metabolites including
urea, creatinine, uric acid, and phosphorus accumulate in the
body's tissues, which can result in a person's death if the
filtration function of the kidney is not replaced.
[0003] Dialysis is commonly used to replace kidney function by
removing these waste toxins and excess water. In one type of
dialysis treatment, peritoneal dialysis (PD), sterile, pyrogen-free
dialysis solution is infused into the patient's peritoneal cavity.
The peritoneal membrane serves as a natural dialyzer and toxic
uremic waste metabolites and various ions diffuse from the
patient's bloodstream across the membrane into the dialysis
solution due to their concentration gradients. At the same time,
fluid is drawn into the peritoneal cavity by an osmotic gradient.
The dialysis solution is removed, discarded and replaced with fresh
dialysis solution on a semi-continuous or continuous basis.
[0004] In the routine care of patients on peritoneal dialysis,
removal of fluid by ultrafiltration plays a significant role in
maintenance of normal body fluid volume and blood pressure. See
Arkouche W., Fouque D., Pachiaudi C., Normand S., Laville M.,
Delawari E., Riou J. P., Traeger J., and Laville M., Total body
water and body composition in chronic peritoneal dialysis patients,
J Am Soc Nephrol 8: 1906-1914, 1997; Lindholm B., Werynski A., and
Bergstrom J., Fluid transport in peritoneal dialysis, Int J Artif
Organs 13:352-358, 1990; and Korbet M. S., Evaluation of
ultrafiltration failure, Advances in Renal Replacement Therapy
5(3):194-204, 1998. The ability of the peritoneal membrane to
remove fluid volume is typically assessed by the standard
peritoneal equilibration test (PET), which measures the dialysate
to plasma (D/P) ratio of selected substance (solute)
concentrations, such as creatinine. For each solute, the transport
rate is categorized as low, low average, high average, and high, in
increasing ranges of the D/P ratio. See Twardowski Z. J., Nolph K.
O., Khanna R., Prowant B. F., Ryan L. P., Moore H. L., and Nielsen
M. P., Peritoneal Equilibration Test, Perit Dial Bull 7: 138-147,
1987; and Smit W., Estimates of peritoneal membrane function-new
insights, Nephrol Dial Transplant 21: ii16-ii19, 2006 (hereinafter
"Smit"). A high D/P ratio of creatinine is a reflection of
ultrafiltration failure, as it is related to high absorption rates
of low molecular weight osmotic agents, such as glucose, from the
dialysate into the patient's blood, and therefore to a rapid
disappearance of the osmotic gradient that enables removal of fluid
from the patient into the dialysate. See Smit. After the
disappearance of the osmotic gradient, fluid from the dialysate can
be reabsorbed across the peritoneal membrane back into the patient.
In such hyper-absorbing patients, the drain volume can be less than
the initial filling volume, and is certainly less than the maximal
desirable ultrafiltration volume. However, PET cannot be used to
monitor the ability of the peritoneal membrane to remove fluid
volume while a PD treatment is being administered. Traditionally,
the total ultrafiltration volume (UFVM) is determined from the
difference in weight between total filling and draining volumes at
the end of a PD treatment, and therefore hyper-absorbing patients
cannot be identified earlier in the treatment cycle.
[0005] Therefore, there is a need for improved monitoring of fluid
removal by ultrafiltration for patients on peritoneal dialysis.
SUMMARY OF THE INVENTION
[0006] The present invention generally relates to peritoneal
dialysis of a patient.
[0007] In one embodiment, a peritoneal dialysis (PD) system for
infusing a volume of PD solution into a patient's peritoneal cavity
in order to perform peritoneal dialysis on the patient includes a
peritoneal cavity monitor (PCM) that measures the volume of fluid
in the patient's peritoneal cavity by segmental bioimpedance
spectroscopy (SBIS), to thereby determine an ultrafiltration volume
of fluid in the patient's peritoneal cavity, and a switch,
controlled by the PCM, for filling the patient's peritoneal cavity
and draining the patient's peritoneal cavity when the
ultrafiltration volume is unchanged over time, significantly
decreased, or decreasing at a significant rate. Alternatively,
instead of the switch, the peritoneal dialysis (PD) system can
include an alarm, controlled by the PCM, for indicating when the
patient's peritoneal cavity is to be drained when the
ultrafiltration volume is unchanged over time, significantly
decreased, or decreasing at a significant rate.
[0008] In another embodiment, a method of peritoneal dialysis of a
patient includes introducing a volume of peritoneal dialysis
solution into the peritoneal cavity of the patient, and measuring
periodically the volume of fluid in the patient's peritoneal cavity
by segmental bioimpedance spectroscopy (SBIS), to thereby determine
an ultrafiltration volume of fluid in the patient's peritoneal
cavity. The method then includes draining the patient's peritoneal
cavity when the ultrafiltration volume is unchanged over time,
significantly decreased, or decreasing at a significant rate. The
method can include refilling the peritoneal cavity of the patient
with another volume of peritoneal dialysis solution.
[0009] The invention has many advantages, including the ability to
drain the peritoneal cavity of a patient after a measured volume of
fluid has accumulated therein, to minimize fluid reabsorption back
into the patient, which is undesirable, thereby enabling
interrupting the dialysis treatment cycle after a desired volume of
fluid has been removed from the patient, or recognizing a
significant reduction in ultrafiltration volume before this volume
is further reduced by reabsorption back into the patient, and
draining the peritoneal cavity and refilling it with another volume
of dialysis fluid and continuing the dialysis treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The foregoing will be apparent from the following more
particular description of preferred embodiments of the invention,
as illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating embodiments of the present invention.
[0011] FIG. 1 is a schematic illustration of an exemplary placement
of electrodes for measurement of fluid volume in the peritoneal
cavity.
[0012] FIG. 2 is a schematic illustration of another exemplary
placement of electrodes and measurement of fluid volume in the
peritoneal cavity.
[0013] FIG. 3 is a side view of the electrodes shown in FIG. 2 and
the peritoneal cavity of a patient in a sitting position.
[0014] FIG. 4 is a schematic illustration of PD treatment and
dialysate control. A switch (SW) is used to control drain or fill
of fluid from or into the peritoneal cavity according to a signal
from the peritoneal cavity monitor (PCM).
[0015] FIG. 5 is a block diagram of an example of a device for
measurement and control of the peritoneal dialysis treatment.
[0016] FIG. 6 is a flowchart for determining fluid exchange during
PD treatment using SBIS.
[0017] FIG. 7 is a graph of the change in fluid volume (%) in the
peritoneal cavity of patient #5 as a function of time (min).
DETAILED DESCRIPTION OF THE INVENTION
[0018] The present invention generally relates to peritoneal
dialysis of a patient. A method of peritoneal dialysis of a patient
includes introducing a volume of peritoneal dialysis fluid into the
peritoneal cavity of the patient. Any suitable peritoneal dialysis
solution (i.e., peritoneal dialysis fluid) known in the art (e.g.,
Delflex.RTM., Fresenius Medical Care North America, Waltham Mass.)
can be used. The volume of PD fluid can be in a range of between
about 1.5 L and about 2.5 L, preferably about 2 L. This known
volume is used to calibrate the bioimpedance measurement of volume.
The method includes measuring periodically the volume of fluid in
the patient's peritoneal cavity during the PD treatment time, for
example at time intervals of about 1 minute, about 5 minutes, about
30 minutes, etc. More frequent measurements provide a higher
temporal resolution, enabling the detection of rapid changes in
ultrafiltration volume. The fluid volume measurements are made by
segmental bioimpedance spectroscopy (SBIS). See Zhu F., Hoenich N.
A., Kaysen G., Ronco C., Schneditz D., Murphy L., Santacroce S.,
Pangilinan A., Gotch F., and Levin N. W., Measurement of
Intraperitoneal Volume by Segmental Bioimpedance Analysis During
Peritoneal Dialysis, American Journal of Kidney Diseases, 42:
167-172, 2003 (hereinafter "Zhu et al."); and U.S. Pat. No.
7,354,417 to Levin et al. 2008. In this SBIS method, eight
electrodes 110, 120, 130, 140, 150, 160, 170, and 180 (e.g.,
standard ECG electrodes) are placed on the body, as shown in FIG.
1. Four electrodes 110, 120, 130, and 140 are electrodes for
injecting current. Electrodes 150 and 170, and 160 and 180 are two
pairs of electrodes for measurement of the voltage between distance
L. The distance between injecting and measurement electrodes is D.
A cable holder 185 can be used to fix the electrodes cable 186 with
a band 187. The volume V of fluid in the peritoneal cavity is
determined based on the relationship
V = K p .sigma. ( L 2 R ) ( 1 ) ##EQU00001##
where K.sub.p is a subject-specific calibration constant, .sigma.
is the conductivity of the fluid in the peritoneal cavity, and R is
the average of R.sub.L and R.sub.R, where R.sub.L=.PHI..sub.L/I and
R.sub.R=.PHI..sub.R/I, where .PHI..sub.L is the voltage measured
between electrodes 160 and 180, and .PHI..sub.R is the voltage
measured between electrodes 150 and 170 upon injection of current I
between electrodes 120 and 140 (left), and electrodes 110 and 130
(right), respectively. K.sub.p can be determined by obtaining
R.sub.LB and R.sub.RB before any fluid is introduced into the
peritoneal cavity, and then obtaining R.sub.LA and R.sub.RA after a
predetermined volume V.sub.C of fluid (e.g., 2 L) is introduced
into the peritoneal cavity of the patient, wherein V.sub.C is the
change in fluid volume (.DELTA.V) between time A and time B, and
then determining K.sub.p from the equation
K p = .sigma. V C L 2 ( R B R A R B - R A ) ( 2 ) ##EQU00002##
where R.sub.B=(.PHI..sub.LB+.PHI..sub.RB)/(2I) and
R.sub.A=(.PHI..sub.LA+.PHI..sub.RA)/(2I).
[0019] Alternatively, SBIS can be performed using a Hydra
bioimpedance device, modified as described below, with the patient
in a supine body position, for example during a standard PET. See
Zhu et al.; Hydra 4200 Analyzer, Xitron Technologgies Inc., San
Diego, Calif. As shown in FIG. 2, the method includes four
electrodes 210, 220, 230, and 240 for injecting current placed on
each hand (210, and 230) and foot (220 and 240), respectively, and
four measuring electrodes 250, 260, 270, and 280 placed on the
lower ribs (250 and 270) and the buttocks (260 and 280) on both
sides of the body. An alternating current (e.g., 5 kHz, in a range
of between about 0.05 mA and about 0.7 mA) is injected continuously
during measurement. With this arrangement of the sensors, the
injected current penetrates the peritoneal cavity on both sides of
the body. The Hydra 4200 Analyzer can be used for measuring only
one segment, and therefore the analyzer was modified by the
addition of a switch (not shown) between segments on either side of
the body. The length of the segment L between electrodes 250 and
260 on one side and electrodes 270 and 280 on the other side can be
measured, for example with a flexible tape. The segmental
extracellular volume V contained within the region of interest 255
is calculated from
V = K s .sigma. ( L 2 R ) ( 3 ) ##EQU00003##
where R is the average segmental resistance measured between the
two sides of the body across the length L, and .sigma. is the
conductivity of the extracellular volume (21.28 mS/cm), and K.sub.s
is a calibration factor determined from the first filling volume
(V.sub.1) and the resistance of the empty (R.sub.E) and the filled
peritoneal cavity (R.sub.F) using the equation
K s = .sigma. V 1 L 2 ( 1 R F - 1 R E ) ( 4 ) ##EQU00004##
[0020] Calibration of the SBIS method to establish the relationship
between change in resistance and fluid volume in the peritoneal
cavity 255 is performed by introducing, as shown in FIG. 3, a known
volume of dialysate at the beginning of treatment. The calibration
factor K.sub.s for this method can be different from the
calibration factor K.sub.p for the eight electrode method described
above. The increase of fluid volume in the peritoneal cavity during
dwell time is considered to be equal to the net ultrafiltration
volume (UFVSBIS) occurring during this period. Drain volume (DVM)
is measured by weighing the last drain volume.
[0021] Turning back to FIG. 1, a connecting cable 188 is used to
transfer signals from the electrodes to the peritoneal cavity
monitor (PCM) 190. The PCM is used to measure the impedance and
transfer a wireless signal, described further below, to control the
switch (SW) 410 shown in FIG. 4 to fill or drain the peritoneal
cavity 255 into drain 420. Alternatively, for use in nonautomated
PD (e.g., continuous ambulatory peritoneal dialysis (CAPD)), an
audible or vibrating alarm can alert the patient or attendant to
drain immediately. After the first drain of fluid out of the
peritoneal cavity 255, and the infusion of 2 liters of fluid into
the peritoneal cavity 255 for the typical four hours of dwell time,
the volume of fluid in the peritoneal cavity 255 is periodically
monitored by SBIS, to monitor the fluid volume in the peritoneal
cavity (V.sub.PC). The peritoneal cavity 255 can be drained when
the volume in the peritoneal cavity 255 has reached a maximal
volume, or when the volume in the peritoneal cavity 255
significantly decreases, such as a relative volume decrease equal
to or greater than about 0.3 L, or when the volume in the
peritoneal cavity 255 significantly decreases over a time interval,
such as more than 10 minutes, or remains stable (i.e., unchanged)
for a period of time, in a range of between about 10 minutes and
about 30 minutes, preferably about 10 minutes, after which time a
new PD dialysate volume (e.g., 2 L) can be infused, until the end
of the treatment (typically four hours). A significant rate of
decrease in the volume of fluid in the peritoneal cavity 255 can be
a rate of volume decrease equal to or greater than about 0.03
L/min. Alternatively, a significant decrease in the volume of fluid
in the peritoneal cavity 255 can be a relative volume decrease
equal to or greater than about 0.3 L.
[0022] As illustrated in FIG. 5, the PCM 190 continuously collects
impedance data from electrode array 505 within a low frequency
range (e.g., between about 1 kHz and about 300 kHz) (impedance
detector 510). A wireless transmitter 520 can be used, using a high
frequency signal produced by signal generator 525 (e.g., 5 MHz), to
send the impedance signal 535 to the receiver 530. The receiver 530
obtains the impedance signal 535 from an antenna 540 and employs
the signal processor 550 to determine whether the switch (SW) 410
should be open or closed for filling or draining according to the
flow chart shown in FIG. 6, displaying the result on display 560.
As shown in FIG. 6, the method starts with bio-impedance analysis
(BIA) of the patient at step 610, followed by a dialysate fill, at
step 620, into the peritoneal cavity of the patient of a
predetermined volume (e.g., 2 L). Then, step 630 is a calibration
of the change in resistance across the distance L from the start of
fill to the end of fill, to determine K.sub.p. The volume of
dialysate in the peritoneal cavity is subsequently calculated at
step 640, and the criterion of slope of change in V.sub.PC during 5
minutes, SV.sub.PC, is established at step 650. If SV.sub.PC is
less than a threshold level (e.g., 0.03 L/min) at step 655, then
the switch 410 (SW) is opened for draining at step 660. If the
absolute value of the change in V.sub.PC (.DELTA.V.sub.PC) is less
than a predetermined amount (e.g., 0.1 L) during a 30 min period at
step 665, then the switch 410 (SW) is opened for draining at step
670. If neither of the conditions 655 and 665 are met, then the
treatment continues until, at step 675, the treatment time is
finished, and the treatment ends at step 680. A person of skill in
the art, such as a physician or a nurse, can adjust or devise
different conditions for draining as appropriate for a particular
patient based on the description provided herein.
[0023] The PCM can be integrated into a peritoneal dialysis (PD)
system, such as the Liberty.RTM. Cycler, that can include a volume
of PD solution to be infused into a patient's peritoneal cavity in
order to perform peritoneal dialysis on the patient, the peritoneal
cavity monitor (PCM) to measure the volume of fluid in the
patient's peritoneal cavity by segmental bioimpedance spectroscopy
(SBIS), to thereby determine an ultrafiltration volume of fluid
accumulated in the patient's peritoneal cavity, and the switch,
controlled by the PCM, for filling the patient's peritoneal cavity
and draining the patient's peritoneal cavity when the
ultrafiltration volume is unchanged, significantly decreased, or
decreasing at a significant rate. Liberty.RTM. Cycler, Fresenius
Medical Care North America, Waltham, Mass.; see U.S. Pat. No.
7,935,074 and U.S. application Ser. No. 12/709,039 published as US
2010/0222735 A1.
[0024] In one embodiment, the determination to drain the patient's
peritoneal cavity and, optionally, exchange the dialysate (i.e.,
refill the patient's peritoneal cavity) during PD treatment, as
shown in FIG. 6, is based on two criteria: 1) the slope of volume
change in the peritoneal cavity (SV.sub.PC) is less than about
-0.03 L/min, in other words the V.sub.PC decreases by more than
about 0.3 L during 10 minutes, or 2) V.sub.PC does not change
during 30 minutes. During the entire treatment time, if the
condition 1) or 2) is met, the switch (SW) opens automatically for
draining, and, after the peritoneal cavity is drained, a new 2 L
volume of dialysate will be infused into peritoneal cavity until
the treatment is completed. Alternatively, an alarm (e.g., an
audible or vibrating alarm) can alert the patient or attendant to
trigger draining.
EXEMPLIFICATION
[0025] Segmental bioimpedance spectroscopy (SBIS) using a Hydra
4200 Analyzer modified as described above was performed with the
patients in supine body position during standard PET. See Zhu et
al. Four electrodes for injecting current were placed on each hand
and foot. Four measuring electrodes were placed on the lower ribs
and the buttocks on both sides of the body. Calibration of the SBIS
method to establish the relationship between change in resistance
and fluid volume in the peritoneal cavity was performed by
introducing a known volume of dialysate in the beginning of
treatment. The increase of fluid volume in the peritoneal cavity
during dwell time was considered to be equal to the net
ultrafiltration volume (UFVSBIS) occurring during this period.
Drain volume (DVM) was measured by weighing the last drain volume.
Dialysate creatinine concentration (DCre) was determined at time
points 0, 2 hrs, and at the end. Plasma creatinine concentration
(PCre) was measured at the beginning of PET. D/P was calculated by
DCre/PCre.
[0026] As shown in Table 1, UFV.sub.Diff represents the change in
net UFVSBIS between the beginning and the subsequent measurement
time. UFVM (0.64, 0.63 and 0.26 L) and UFVSBIS (0.42, 0.54 and 0.05
L) were observed for each Patient 1, 2, and 3, respectively. Mean
UFVM did not differ from the net UFVSBIS (0.51.+-.0.22 vs
0.34.+-.0.26 L) and mean DVM (2.62, 2.5 and 2.25 L for each
patient) was approximately equal to the DVSBIS (2.0, 2.2 and 2.21 L
for each) estimated by SBIS (2.46.+-.0.19 vs 2.13.+-.0.13 L).
[0027] The results shown in Table 1 provide information on the
relationship between the change in UFV and transport of creatinine
during PET. The availability of dynamic information on the
ultrafiltration volume helps to understand the characteristics of
the peritoneal membrane. The information might be useful for
clinical practice, to adjust the PD procedure according to
individual characteristics of the peritoneal membrane.
[0028] Additionally, the periodic measurement of the
ultrafiltration volume enables draining the patient's peritoneal
cavity at or near a maximum UFV.sub.Diff, which, as shown in Table
1, occurred for Patient 1 at about 2 hours of dwell time and for
Patient 2 at about 3 hours of dwell time, and also enables
identifying a patient whose peritoneal membrane is absorbing fluid
from the dialysate from the beginning of the treatment and
therefore showing a negative UFV.sub.Diff, such as Patient 3.
TABLE-US-00001 TABLE 1 Ultrafiltration volume results for 3
patients during PD treatment Dwell UFV.sub.Diff UFV.sub.Diff
UFV.sub.Diff time [L] [L] [L] D/P D/P D/P [Hours] Patient1 Patient2
Patient3 Patient1 Patient2 Patient3 0 0 0 0 0.02 0.27 0.02 1 0.53
0.23 -0.25 2 1 1.113 -0.5 0.35 0.71 0.55 3 0.53 1.98 -0.73 4 0.42
0.54 0.05 0.52 0.78 0.70
Optimal Dwell Time Example
[0029] Two pairs of electrodes were placed on both lateral aspects
of the abdomen. Segmental spectroscopy (sBIS) was used to
continuously monitor fluid changes during the dwell. UFV was
calculated from the change in intraperitoneal fluid volume after 2
L PD fluid instillation. Optimal dwell time (ODT) is the time
between start of PD and the point when fluid reabsorption is
detected. Patients were studied twice in supine position using
manual PD: 1) study1, regular procedure with 4 hours dwell time
(DT), with sBIS monitored throughout the exchange; 2) study2 ODT
procedure, dialysate was drained when the rate of change in fluid
volume became negative (fluid being absorbed) or was flat (i.e.,
unchanged) for more than 10 minutes. Actual UFV (aUFV) was defined
as the weight difference between drain and fill volumes.
[0030] Preliminary results in the three patients (Table 2) show
that aUFV was identical to UFV estimated by sBIS. In the second
study, the optimal time to drain was within the first two hours of
dwell. FIG. 7 shows the changes in peritoneal fluid volume during
PD in patient #5.
TABLE-US-00002 TABLE 2 DT, Study1 UFV, ODT, Study2 UFVMax, Patient
min aUFV, L L min aUFV, L L #4 240 0.406 0.4 120 0.266 0.226 #5 245
0.04 -0.007 100 0.106 0.115 #6 212 0.396 0.327 87 0.368 0.312
[0031] By continuously monitoring changes in intraperitoneal fluid
volume, sBIS allows maximization of UFV by optimizing DT. Any
plateau or decrease in UFV should prompt dialysate drainage. An ODT
could be provided for every exchange, which is particularly
advantageous with automated PD. Although additional exchanges may
be required to reach a Kt/V target, an important advantage of the
technique is its ability to maximize ultrafiltration volume.
[0032] The relevant teachings of all patents, published
applications and references cited herein are incorporated by
reference in their entirety.
[0033] While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *